L12 phase formation and giant exchange anisotropy in Mn3Ir/Co–Fe bilayers

The degree of order S of Mn–Ir layers and the exchange anisotropy of Mn–Ir/Co–Fe bilayers were investigated for various chemical compositions of Mn–Ir layers, underlayer materials, and underlayer thicknesses. It was found that: (1) The compositional range over which L1₂-phase Mn₃Ir could be formed is 22–32 at% Ir and giant exchange anisotropy is obtained in this range. (2) Ru is favorable as an underlayer material for avoiding interdiffusion with the Mn–Ir layer during deposition on the temperature elevated substrate. (3) The underlayer thickness could be reduced to 5 nm while maintaining a giant exchange anisotropy in excess of 1 erg/cm².     

Phenanthrene adsorption from solution on single wall carbon nanotubes

Phenanthrene was adsorbed from ethanol solution to the surface of single wall carbon nanotubes, which were previously physically and chemically characterized. Different anionic surfactants were added in the solutions to enhance the phenanthrene solubility and apparently have also improved the dispersion of two respective nanotube samples used. Adsorbed amount was determined through the concentration difference measured by UV-visible spectrophotometry. Results suggest that adsorption of phenanthrene is extremely improved in the case of nanotube purified with higher quality. These findings were confirmed by X-ray photoelectron spectroscopy. The influence of the surfactant on the adsorption kinetics of phenanthrene is suggested to be significant as well.     

Cis double allylation of cyclopropenes using cyclopropylindium reagents

The successive double allylation of cyclopropenes with allylindium sesquiiodide and allyl iodide proceeded with a cis-addition mode in the presence of other organometallics (e.g. Grignard reagent, cuprate, Et(2)Zn and Et(3)Al), giving the corresponding cis-diallylcyclopropanes in high yields.     

Spectrophotometric determination of cobalt(II) and cyanocobalamin with vanillilfluorone and its applications

Spectrophotometric determination of cobalt(II) was accomplished with vanillilfluorone (VF) in the presence of dimethylbenzyltetradecylammonium chloride (Zephiramine, Zep). In the determination of cobalt(II), Beer's law was obeyed in the range of 24-470 ng/ml, with an effective molar absorption coefficient (at 575 nm) and relative standard deviation of 1.35×10(5) l mol(-1) cm(-1) and 0.66% (n=5), respectively. The composition ratio of the colored complex was determined by the mole ratio and continuous variation methods, and it was found to be Co(II) : VF : Zep=1 : 2 : 4. Analysis of cyanocobalamin by the same procedure showed that cyanocobalamin could be determined in the concentration range of 0.5-0.11 μg/ml using the proposed method.     

A chip-based miniaturized format for protein-expression profiling: the exploitation of comprehensively produced antibodies

Numerous antibodies have been developed and validated in recent years, and show promise for use in novel functional protein assays. Such assays would be an alternative to pre-existing comprehensive assays, such as DNA microarrays. Antibody microarrays are thought to represent those functional protein assays. While a variety of attempts have been made to apply DNA microarray technology to antibody microarrays, a fully optimized protocol has not been established. We have been conducting a project to comprehensively produce antibodies against mouse KIAA ("KI" stands for "Kazusa DNA Research Institute" and "AA" are reference characters) proteins. Using our library of antibodies, we established a novel antibody microarray format that utilizes surface plasmon resonance (SPR) technology. A label-free real-time measurement of protein expression in crude cell lysates was achieved by direct readout of the bindings using SPR. Further refinement of the antibody microarray format enabled us to detect a smaller quantity of target proteins in the lysate without the bulk effect. In this review, we first summarize available antibody array formats and then describe the above-mentioned format utilizing updated SPR technology.     

Chemical Synthesis of Interleukin-2 and Disulfide Stabilizing Analogues

Chemical protein synthesis allows the construction of well-defined structural variations and facilitates the development of deeper understanding of protein structure–function relationships and new protein engineering strategies. Herein, we report the chemical synthesis of interleukin-2 (IL-2) variants on a multimilligram scale and the formation of non-natural disulfide mimetics that improve stability against reduction. The synthesis was accomplished by convergent KAHA ligations; the acidic conditions of KAHA ligation proved to be valuable for the solubilization of the hydrophobic segments of IL-2. The bioactivity of the synthetic IL-2 and its analogues were shown to be equipotent to recombinant IL-2 and exhibit improved stability against reducing agents.     

Spin-flip approach within time-dependent density functional tight-binding method: Theory and applications

A spin-flip time-dependent density functional tight-binding (SF-TDDFTB) method is developed that describes target states as spin-flipping excitation from a high-spin reference state obtained by the spin-restricted open shell treatment. Furthermore, the SF-TDDFTB formulation is extended to long-range correction (LC), denoted as SF-TDLCDFTB. The LC technique corrects the overdelocalization of electron density in systems such as charge-transfer systems, which is typically found in conventional DFTB calculations as well as density functional theory calculations using pure functionals. The numerical assessment of the SF-TDDFTB method shows smooth potential curves for the bond dissociation of hydrogen fluoride and the double-bond rotation of ethylene and the double-cone shape of H₃ as the simplest degenerate systems. In addition, numerical assessments of SF-TDDFTB and SF-TDLCDFTB for 39 S₀/S₁ minimum energy conical intersection (MECI) structures are performed. The SF-TDDFTB and SF-TDLCDFTB methods drastically reduce the computational cost with accuracy for MECI structures compared with SF-TDDFT.